to long-term care, office-based, and residential facilities. We coded case-days as “1,” encompassing the index event and subsequent events, whereas control-days were coded as “0,” encompassing remaining days in the observation window. Assuming prescription fills denoted consumption of medication, we imputed medication treatment over time defined by presence or absence of filled prescriptions; national drug codes and procedure codes for buprenorphine and naltrexone have been detailed elsewhere.13 We coded medication days as “1” and nonmedication days as “0” (reference group). To assess polysubstance use, we used ICD-9 and ICD-10 codes during encounters to identify cooccurring SUDs at the time of OUD pharmacologic treatment initiation or during the 6 months preceding treatment. We subsequently stratified between participants with OUD and cooccurring SUD, as well as individuals without recent SUD diagnoses. Finally, we extracted data on age, sex, self-reported race and ethnicity, cooccurring psychiatric diagnoses (ie, mood, anxiety, psychotic, and personality disorders), Charlson comorbidity index, and insurance status for purposes of sample description.
